GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 16 Aug 2018, 01:12

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# DS - inequ

Author Message
Manager
Joined: 14 Jun 2007
Posts: 158
Location: Vienna, Austria

### Show Tags

02 Nov 2008, 03:36
00:00

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions

### HideShow timer Statistics

guys
can you help me with this ... don´t have an OA!

cheers

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

Attachments

Doc1.doc [89 KiB]

VP
Joined: 17 Jun 2008
Posts: 1474

### Show Tags

02 Nov 2008, 04:17
E.

From stmt1: 7x - 2y > 0, x > 0 and y can be +ve or -ve.
From stmt2, x+y > 0 and again, y can be +ve or -ve.

Combining two also gives x > 0 with y having any values.
VP
Joined: 30 Jun 2008
Posts: 1004

### Show Tags

02 Nov 2008, 07:05
scthakur wrote:
E.

From stmt1: 7x - 2y > 0, x > 0 and y can be +ve or -ve.
From stmt2, x+y > 0 and again, y can be +ve or -ve.

Combining two also gives x > 0 with y having any values.

can we not do the following ??

Combining the two statements .. we can solve the two inequalities as we solve simultaneous equations

eliminating x
a) 7x-2y >0 (stmt 1)
b) 7x+7y > 0 (stmt 2 * 7)

a-b => -9y > 0 or y<0

hence C

Am I doing anything wrong ?
_________________

"You have to find it. No one else can find it for you." - Bjorn Borg

Manager
Joined: 09 Jul 2008
Posts: 107
Location: Dallas, TX
Schools: McCombs 2011

### Show Tags

02 Nov 2008, 07:33
amitdgr wrote:
scthakur wrote:
E.

From stmt1: 7x - 2y > 0, x > 0 and y can be +ve or -ve.
From stmt2, x+y > 0 and again, y can be +ve or -ve.

Combining two also gives x > 0 with y having any values.

can we not do the following ??

Combining the two statements .. we can solve the two inequalities as we solve simultaneous equations

eliminating x
a) 7x-2y >0 (stmt 1)
b) 7x+7y > 0 (stmt 2 * 7)

a-b => -9y > 0 or y<0

hence C

Am I doing anything wrong ?

I'll pick E.

stmt 1: y can be +ve or -ve
stmt 2: Just says -x < y. y can be -5 and x can 10. Or y can be 10 and x can be 5. Insuff
VP
Joined: 17 Jun 2008
Posts: 1474

### Show Tags

03 Nov 2008, 00:29
amitdgr wrote:
can we not do the following ??

Combining the two statements .. we can solve the two inequalities as we solve simultaneous equations

eliminating x
a) 7x-2y >0 (stmt 1)
b) 7x+7y > 0 (stmt 2 * 7)

a-b => -9y > 0 or y<0

hence C

Am I doing anything wrong ?

Subtracting two inequalities is not correct all the time. For example, 2 > 0 and 3 > 0 but, (2-3) < 0. However, additions is ok.
Manager
Joined: 24 Sep 2008
Posts: 180
Schools: MIT / INSEAD / IIM - ABC

### Show Tags

03 Nov 2008, 02:01
scthakur wrote:
amitdgr wrote:
can we not do the following ??

Combining the two statements .. we can solve the two inequalities as we solve simultaneous equations

eliminating x
a) 7x-2y >0 (stmt 1)
b) 7x+7y > 0 (stmt 2 * 7)

a-b => -9y > 0 or y<0

hence C

Am I doing anything wrong ?

Subtracting two inequalities is not correct all the time. For example, 2 > 0 and 3 > 0 but, (2-3) < 0. However, additions is ok.

My two cents, since we don't know wether y>0 or <0 so we can't do the substraction...as our friend explained using example: 2 > 0 and 3 > 0 but, (2-3) < 0.
VP
Joined: 30 Jun 2008
Posts: 1004

### Show Tags

03 Nov 2008, 02:37
scthakur wrote:
amitdgr wrote:
can we not do the following ??

Combining the two statements .. we can solve the two inequalities as we solve simultaneous equations

eliminating x
a) 7x-2y >0 (stmt 1)
b) 7x+7y > 0 (stmt 2 * 7)

a-b => -9y > 0 or y<0

hence C

Am I doing anything wrong ?

Subtracting two inequalities is not correct all the time. For example, 2 > 0 and 3 > 0 but, (2-3) < 0. However, additions is ok.

Ok I get it ..... Is adding 2 inequalities fine ?
_________________

"You have to find it. No one else can find it for you." - Bjorn Borg

VP
Joined: 17 Jun 2008
Posts: 1474

### Show Tags

03 Nov 2008, 02:49
1
amitdgr wrote:
Ok I get it ..... Is adding 2 inequalities fine ?

Addition is the only thing that should be done on inequalities.

For example, a > 0, b > 0 and hence (a+b) > 0.
Alternatively, a < 0, b < 0 and hence (a+b) < 0.
VP
Joined: 30 Jun 2008
Posts: 1004

### Show Tags

03 Nov 2008, 03:07
scthakur wrote:
amitdgr wrote:
Ok I get it ..... Is adding 2 inequalities fine ?

Addition is the only thing that should be done on inequalities.

For example, a > 0, b > 0 and hence (a+b) > 0.
Alternatively, a < 0, b < 0 and hence (a+b) < 0.

Thanks scthakur +1

--== Message from GMAT Club Team ==--

This is not a quality discussion. It has been retired.

If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

_________________

"You have to find it. No one else can find it for you." - Bjorn Borg

Re: DS - inequ &nbs [#permalink] 03 Nov 2008, 03:07
Display posts from previous: Sort by

# Events & Promotions

 Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.